1. Field of the Invention
The present invention relates to a simple architectonics high-precision encoder, a slim lens-implement using the encoder, and a digital camera using the lens-implement.
2. Description of the Related Art
Conventionally, with a growing demand for a smaller and slimmer digital camera in the digital camera market, a slim lens-implement incorporated into a digital camera has been required.
As one of the methods of providing a slimmer lens-implement, a lens-implement based on a bent-optical-axis optical system has been proposed. For a slimmer device, the Applicant has proposed a lens-implement configured by arranging in parallel a plurality of units forming a lens-implement (for example, a patent literature 1).
For a lens-implement based on the slimmer and bent-optical-axis optical system, an electronic zoom is not demanded in the recent digital camera market, but a request for an optical zoom is growing. Therefore, a lens-implement of a bent-optical-axis optical system having a built-in optical zoom has been proposed. (For example, refer to Japanese Patent Application Laid-open No. 2003-066309, abstract, FIGS. 3 and 5; Japanese Patent Application Laid-open No. 2002-290806, claim 6, paragraphs [0038] and [0041], FIGS. 2 and 3.) In the lens-implement of a conventional camera, a lens frame unit holding a lens for a zoom and focusing is freely transferred in the optical axis direction at an instruction from a control device.
Since a lens frame unit and a drive unit for driving the lens frame unit are individually manufactured, a coupling mechanism is required to transmit a driving force to transmit the driving force of the drive unit to the lens frame unit.
In this case, it is necessary to amend various displacements such as the displacement between the units, the displacement in the horizontal direction relative to the lens frame unit, etc. However, there have been the methods for coupling the units with the above-mentioned displacements easily absorbed and amended. Among them, for example, there is a configuration proposed in which a spring member that indicates elastic deformation is used for a coupling member, and the spring member has the elasticity allowing a deformation on the plane normal to the optical axis or perpendicular to the optical axis while the spring member has no elasticity in the optical axis direction. (For example, refer to Japanese Patent Application Laid-open No. Hei 09-061692, paragraph [0018], FIG. 1, and Japanese Patent Application Laid-open No. Hei 09-033782, abstract, and FIG. 1.)
As a type of encoder for continuously detecting the position, a position detection device using a magnetic resistance element is proposed. The position detection device is a high-precision, possible down sizing and capable of easily consecutive detecting transfer positions, and therefore is specifically used in detecting an amount of transfer of a lens.
In the meantime, the position detection device using the magnetic resistance element has the problem that a magnetic sensor cannot correctly read the magnetic scale unless the magnetic resistance element (magnetic sensor) and the magnetic scale can be maintained at a predetermined interval.
Accordingly, there has been the position detection device proposed by providing a simple adjusting mechanism to maintain a constant interval between the magnetic sensor and the magnetic scale (for example, see Abstract of the Disclosure, and FIG. 1 of Japanese Patent Application Laid-open No. 2000-002559.)